Nesting Habitat Characteristics and Breeding Performance of Dalmatian Pelicans in Lake Mikri Prespa, NW Greece

Abstract

-Dalmatian Pelicans (Pelecanus crispus) in Lake Mikri Prespa nest on islands of Common Reed (Phragmites) rhizomes formed at the interface between marsh and open water and mostly ranging from 6-80 m2 in area. Nest density from 1984 to 1996 varied from 0.12 to 1.2 nests/m2. Large islands were not more densely occupied than smaller ones. Higher nest densities were observed in the second and third year that a site was used. Islands used for nesting were degraded by weather, water and use by the birds and shrank in size by 1-55% each year; thus some were abandoned and new ones colonized each year. On the average, sites were used for three years in succession, but initially larger sites were used much longer. Nest site quality was related to island rigidity and the availability of nesting material on it. Numbers of breeding pelicans at Prespa are probably limited by the availability of suitable nest sites and, especially, larger islands, since breeding success is positively correlated with the mean nesting assemblage size (number of breeding attempts/number of sites). Artificial nesting rafts are likely to be more successful the more their features comply with the above findings and the more they enhance overall colony compactness. Received 15 April 2001, accepted 18 August 2001.